Over at the Tale of Painters blog member Third Eye Nuke has recently made a post on how to paint blood, giving the example of a stunning Tyranid model (I'm not sure which model it is since I don’t really know the ‘Nids!).
I really like this method of painting blood although I have to admit it is far beyond my current level to achieve.
A mix of paint brands are used, including Games Workshop, Vallejo and Tamiya to create a very realistic blood effect. I really love this.